1. Field of the Invention
The present invention relates to winding arrangements such as warp beams for the warping of elastic thread having predetermined extensions. Thread paid out from a spool of a creel is driven by payout rollers driven at a first predetermined circumferential speed, are stretched by means of tension rollers driven at a higher, second, predetermined circumferential speed before being finally warped onto a warp beam driven on a warping machine at a third circumferential speed of the warp beam wind. In this apparatus, the relationship between two sequential winding speeds is constant and their relationship to the other circumferential winding speed is alterable in dependence upon an operational quantity.
2. Discussion of the Relevant Art
In a warping arrangement of this type (LIBA 22E), the payout rollers and the tensioning rollers are driven at a constant speed so that the relationship between the first and the second circumferential speeds is constant. The warping machine is so driven that for a circumferential speed of the warp beam wind, for a given degree of stretch, a compensation is provided to thread taken from the creel in dependence upon the length of the thread, by means of a compensating eccentric cam.
In this respect, one must face the fact that elastic threads are not wound on their spools with constant tension in relationship to the thread length. The tension difference can run as high as 10% and it is not permissible to transfer this difference to a warp beam because then, with the same length of thread on the warp beam, different diameters are obtained. A compensating eccentric cam is unfortunately suited only for a particular spool size and a particular thread number. Where different spools are used it is necessary to provide a different compensating cam. If the situation arises where the spools are of a type not previously used, it is necessary to manufacture a new compensating eccentric cam. This requires the need for time consuming experimentation to obtain the proper form. With this type of compensation, it is also not possible to warp the threads with constant tension since the compensating eccentric cam can only provide for an average tension compensation and tension changes which occur during prolonged machine rest periods are not taken into account at all.
It is further known (DE-GM No. 6929186) to take off single threads over a slidingly coupled, driven spool and despite changing payout speeds, maintain a constant tension in that the spool is braked in dependence upon the tension of its individual thread. For this purpose there is provided a rotatable moment balance which carries a roller on each arm of a twin armed lever. This lever is biased by a braking spring so that the forces working on the thread lies in the order of magnitude of the braking spring force.
Accordingly, there is a need for a warping or similar arrangement of the foregoing type wherein the warping on the warp beam is achievable with higher extension accuracy and without the need for a compensating eccentric cam.